Graphic images and designs have been formed on metal surfaces for a variety of uses for many years. One common practice employed in the electronics industry is to create printed circuit boards using a technique known as “print and etch”. This method uses a polymeric photoresist that is laminated onto a copper clad dielectric medium. The photoresist is photopolymerized with an ultraviolet light in selected areas, and the unpolymerized resist is washed off with chemicals, exposing the copper in certain areas. The exposed copper is then etched with strong acids to dissolve and chemically remove the copper. The remaining polymerized resist is then removed with additional harsh and environmentally damaging chemicals, to yield the patterned circuit. Numerous variations of this technique are used today thoughout various industries to provide patterned metal surfaces for a wide variety of uses. The problem with all of these techniques is that they require expensive equipment, they use large quantities of toxic chemicals that are harmful to the environment, and thus are subject to strict government regulation.
Alternate techniques seek to provide visual designs on metal surfaces by mechanically carving into the metal surface, removing some measurable amount of material by cutting, burning, or otherwise vaporizing the metal using cutting tools or lasers. Still other techniques emboss or stamp the metal surface to create a design.
Each of these techniques removes metal or distends the metal in one way or another, creating a three dimensional surface with measurable texture. They are limited in that they can only be used on metal substrates of sufficient thickness to allow for metal removal. And they are costly and slow. There is a continuing need to improve the quality, reduce the cost, and to simplify the manufacture of graphic images on a two dimensional metal surface that does not harm the environment.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.